For security reasons, it is frequently required to search a person, prior to entering a densely populated area (restaurants, malls, etc.), for the presence of concealed weapons or other means necessary for conduction of acts of violence. Such weapons are generally metallic or contain metallic components.
This kind of threat must be detected at a distance, since conventional metal detection systems (a gate or a hand-held metal detector), or a personal body search, necessitate the near proximity of the security personnel to the suspected person, and thus dangerously expose the personnel to this form of violence.
Prior art methods and systems for the remote detection of such threats include high-resolution radar systems capable of penetrating clothes covering the metallic objects. These systems, however, need a trained observer to monitor the obtained picture.
Passive radio wave systems have also been proposed, which pick up the RF region of the blackbody radiation emitted by the suspected person. These systems, however, employ detectors that require extreme cooling and are very expensive. In addition, again, a trained operator must monitor the display of the system. The detection range of these devices is rather limited.